There is a distinct difference between a "fact" and a "factoid." A fact is something that is irrefutably true. In science, a scientific fact is something that has been observed over and over again from multiple standpoints. As such, it is accepted as being "true." However, it is important to note that, in science, nothing is ever settled. If there is a change or alteration, or if something comes along and disproves the fact, well, then it is no longer a fact. That is science. It is never set in stone. On the other hand, a factoid is an assumption or speculation that is reported and repeated over and over to the point that it becomes accepted as fact.
Note the difference here. A fact is based on observations that have been verified many times. A factoid is a statement based on an assumption—something that has never been confirmed.
Often, these factoids can lead to significant misunderstandings about the universe and how it operates. For example, a full stomach will make you short of breath, but it won't give you cramps. Thus, the belief that you need to wait an hour, or a half hour, or fifteen minutes after eating before going swimming (lest you get cramps and drown) is simply that: A belief. It is not based on any factual evidence.
In this infograph David McCandless, from Information is Beautiful, outlines 50 facts that, well, simply aren't factual. How many did you believe in, and are there any that are missing? Click here for a larger version. Get more in this awesome book. "With a portion of its content crowd-sourced from McCandless’s international following, [his book] Knowledge is Beautiful achieves a revolutionary and democratic look at the key issues from questions on history and politics, the facts of science, streams of literature, and much more." You'll definitely want to grab this.